December in Grapevine is the cloudiest month of the year. In December, the weather in Grapevine is typically warm. Average daily high temperature in December is about 12 degrees above zero. On average, Grapevine has 15 partly cloudy, 12 sunny, and 4 rainy days in December. The rains are usually moderate. December as well as January, July, and August is considered the most uncomfortable time to visit Grapevine.